Guide for use in gaining stair-stringers



(No Model.)

R. MARTIN. GUIDE FOR USE IN GAINING STAIR STRINGERS.

No. 487,889. Patented Dec. 13, 1892.

Fig. ,9.

'El 1 2 J Mt WITNEsEnE-a UNITED STATES PATENT OFFICE.

ROBERT MARTIN, O-F PHILADELPHIA, PENNSYLVANIA.

GUIDE FOR USE IN GAINING STAlR-STRINGERS.

SPECIFICATION forming part of Letters Patent No. 487,889, dated December13, 1892..

Application filed May 17 1892.

To all whom it may concern:

Be it known that I, ROBERT lVIARTIN, a citizen of the United States,residing at Philadelphia, in the county of Philadelphia and State ofPennsylvania, have invented a new and useful Improvement in Guides orGages for use in Gaining Stair-stringers.

The object of my invention is to render the manufacture ofstairstringers economical, uniform, and rapid by gaining them with amachine-cutter or routing-tool of simple and uncomplicated constructionand doing away with the previous marking out of the Work.

My invention consists, first,in a guide or gage of the outline of onecomplete step, capable of being joined to as many other similargages asmay be required, and the whole guiding a cutter pressed against theirsides in gaining a complete stringer at one continuous operation.

It also consists in forming the gage in two pieces, one being of theoutline of the edge of the step and the other of the outline of theinner corner of the step, and making the two pieces adjust-ablyattachable to each other, so that the length of the tread-gains andrisegains may be varied as desired.

It also consists in means for fastening the series of gages to the plankto be gained, so that the Whole may be moved by hand under a stationarycutter mounted on a vertical shaft.

It also consists in an attachable piece for use when the tread-gains aredesired to be as narrow as the rise-gains.

Referring to the drawings, Figure l is a perspective view of one of myimproved gages of the preferred form. Fig. 2 is a perspective View ofthe attachable piece for usewhen cutting narrow tread-gains. Fig. 3 is aplan view of Fig. 1. Fig.4 is a plan View of Fig. 2. Fig. 5 is anelevation of Fig. 3. Fig. 6 is an elevation of Fig. 4. Fig. 7 isperspective view of a complete stair-stringer, and Figs. 8 and 9 areperspective views of the gains for one step to illustrate the method ofcutting.

Stair-stringers have heretofore been gained by hand or by a movablecutter working in the slots of a templet adapted to cut the gains forone step only and requiring the stringer to be marked out and to bemoved and fastened at each step, as shown in patent to Wil- Serial No.433.295. (No model.)

liarn H. Parry, No. 374,493, dated December v6, 1887.

A stair-stringer is a plank grooved or gained,

as shown in Fig. 7, to receive the ends of the boards forming the stepsof a flight of stairs.

The tread-gaint receives the tread or horizontal board of the step andthe rise-gain 7" receives the end of the rise-board of the step. Thetread extends, slightly beyond the end of the rise and is molded orrounded to form what is termed a nosing, the gain for which is shown atn.

My improved gage consists of two main portions A and B, in general ofapproximately-rectangular crosssection, the part B being a simple rightangle and the part A having two legsa and a'substantially at rightangles with each other, but connected by an intermediate rounded portionP to form the nosing of the gains. The part A is provided with dovetailgrooves g g, and the part B is provided with corresponding dovetailtongues h h.

In use a piece similar to A is attached to the end b of the piece B, andso on until a series of gages are joined together sufficient to gain theentire stringer. By means of the dovetail tongues and grooves the gagesand portions of gages are slid upon each other until adjusted to thelength of tread and rise required and then fastened in their adj ustedpositions by flat-headed set-screws at s and s. The whole series ofgages is then fastened to the work or plank to be gained by screwspassing through holes at S. After fastening the series of gages to theplanks I pass the plan k, with the gages attached, under a cuttermounted on the lower end of a rotating vertical shaft and at the properheight above the operating-table to give the desired depth of gain andmove the work by hand, so that the cutter or routing-tool shall alwaysbe pressed firmly against the inner edge d e f i Z of the series ofgages until all the grooves or gains are cut out.

In practice it is usual to cut the tread-gain wider than the rise-gainfor obvious reasons. I therefore prefer to go over the entire work firstwith a narrow cutter having a diameter equal to the rise of the step,cutting a gain of the form shown in Fig. 8, in which the nosing only ofthe tread is of the required width. Then, using a wider cutter of adiameter equal to the required width of tread, I cut a single straightline along 6 f 1', making the gain as shown in Fig. 9. Of course it isobvious that the width of the space N must equal the diameter of thewide cutter or the width of the required tread. I therefore provide anextra piece P, having a space N equal to the diameter of the narrowcutter, to be used in cases where the tread is desired to be narrower oronly of the width of the rise. This piece P has a-dovetail tongue h andis fastened to the gage by a set-screw at 8 It has, also, a countersunkhole at S to register with the hole S in the main gage.

I prefer to make myimproved gages of brass. In gaining stringers on thereverse side I merely turn the gages upside down. Of course it isobvious that the part A may be provided with tongues and the part B withgrooves, or each may have one tongue and one groove, without departingfrom the spirit of my invention. I

Having, as above, fully described my in vention and the best methodknown to me of using the same, what I claim, and desire to secure byLetters Patent, is-

1. A guide or gage foruse in gaining stairstringers, the inner orworking edge of which is of the outline of the outer and upper sides ofthe stringer-grooves, provided with means for attaching a number of thegages together for gaining stringers for a number of steps at oneoperation, substantially as described.

2. A gage for the purpose set forth, consisting of two pieces A and B,together forming the outline of one rise and one tread, adjustablyattachable to each other, and capable of being adj ustably attached toother similar gages for varying the length of tread and rise of thesteps and guiding a cutter in gaining a stringer for the number of stepsrequired in one continuous operation.

3. A gage for use in gaining stair-stringers,

consisting of two pieces A and B, together I forming the outline of onerise and one tread,

sliding on each other by means ofdovetail tongues and grooves,substantially as shown and described.

4. In a gage for use in gaining stair-stringers, the combination of apiece of the outline of the outer edge of the steps, another piece ofthe outline of the inner corner of the steps, dovetail tongues andgrooves by which the two pieces may be adjusted, set-screws for securingthem in their adjusted position, and means for attaching the whole tothe plank to be gained, substantially as shown and described.

5. An adjustable gage for gaining stairstringers, in combination with adetachable piece P, in which the width of the space for gaining thenosing of the tread-gains is less than the corresponding space in themain gage, substantially as shown and described.

6. A gage for gaining stair-stringers, consisting of two pieces, eachpiece being substantially a right angle formed in a bar ofsubstantially-rectangular cross-section, one of said pieces havingarounded offset at the corner for forming the nosing on the tread-gainand both legs of each piece provided with dovetail tongues or grooves,so that either one piece may be adj ustably attached to either end-ofthe other piece, substantially as shown and described.

7. The combination of two or more gages A- 1 and described.

ROBERT MARTIN. Witnesses:

EDW. O. DOLMAN, J. WALTER ZEBLEY.

